A centrifuge has been widely used in the fields of medicine, pharmacy, genetic engineering, and the like. Generally, the centrifuge having a maximum rotation speed in the range of 10,000 to 30,000 rpm is operated in the state where a rotation chamber used for rotating a rotor has an atmospheric pressure. In this case, a temperature of a sample may increase due to an increase in heat generated by the friction between the rotor and air generated during the rotation of the rotor. For this reason, in many cases, the centrifuge is attached with a cooling device such as a cooler using a coolant or a Peltier element. In this type of centrifuge, a user sets operation conditions such as a rotation speed, an operation time (separation time), and a holding temperature (set temperature) through a panel operation unit in accordance with the sample (specimen) to be separated.
Subsequently, the rotor having the sample inserted thereto is set in the rotation chamber, and a door is closed. When a start switch of the operation unit is pushed, the rotation of the rotor starts. When the rotor is accelerated up to a set rotation speed, the rotor uniformly rotates at the set rotation speed. When the rotor continuously rotates at the uniform set rotation speed and the set operation time is elapsed, the rotation of the rotor is decelerated, and the rotor stops. Subsequently, the user opens the door to extract the rotor, and extracts the separated sample from the rotor.
In such a series of centrifugal separation operations, it is not practical that the user continuously waits before the centrifuge to monitor the operation state from a time when the rotation of the rotor starts until the rotation of the rotor stops. This is because several minutes, several hours, or several tens of hours may be taken for the centrifugal separation operation. Accordingly, in many cases, the user pushes the start switch of the centrifuge so as to accelerate the rotor up to the set rotation speed, checks if the rotor arrives at the uniform set rotation speed, and then leaves from the centrifuge, performs other operations, or starts to prepare the next centrifugal separation operation. This is because the rotor rotating at a uniform rotation speed without the acceleration or deceleration is reliably rotated in many cases.
When the operation of the centrifuge stops after the set operation time is elapsed, a stop buzzer or a stop melody beeps. However, it is possible to easily recognize the stop state of the centrifuge when the user is close to the centrifuge, but it is difficult to listen to the buzzer or melody when the user is away from the centrifuge. For this reason, the user leaves from the centrifuge after the rotor starts to be accelerated up to the uniform set rotation speed, and returns to the centrifuge after the set operation time is elapsed. The returning timing may be set based on the set operation time or may be set based on a time displayed on an indicator in the case where a remaining operation time is displayed on the indicator as in JP-H06-079199-A. In addition, in the case where the user returns to the centrifuge immediately before the operation time is elapsed, the rotor may be not in a stop state but in a rotation state. In this case, during a time when the rotor starts to be decelerated to stop, the user of the centrifuge waits before the centrifuge in many cases so as to immediately extract the sample.
In the centrifuge, a best suitable rotor is selected from plural types of rotors in accordance with the separation condition or the sample to be separated, and the centrifuge is operated in a changed operation condition. Since there are plural types of rotors such as a light and small rotor (having small inertia moment) and a heavy and large rotor (having large inertial moment), the acceleration time until the set rotation speed or the deceleration time from the set rotation speed until the stop is different in accordance with the rotor to be used. Of course, the acceleration time and the deceleration time are short in the case of the rotor having small inertia moment, and are long in the case of the rotor having large inertial moment. For example, the acceleration time and the deceleration time are 20 minutes or more in the case of a certain large-sized rotor.
Further, even in the case of using the same rotor, the acceleration time until the rotor is stabilized at the set rotation speed or the deceleration time until the rotor stops from the set rotation speed is different in accordance with a difference in the amount of the set sample. In the technology disclosed in JP-H06-079199-A, the remaining operation time (the operation time when the rotor rotates at the uniform rotation speed) of the centrifuge is displayed, but the time required for the deceleration is not displayed. Accordingly, the user of the centrifuge needs to estimate the acceleration time and the deceleration time from the past operation record. However, since many users do not accurately recognize the acceleration time or the deceleration time, the users unthinkingly wait before the centrifuge while uselessly spending time without having any idea about the time when the rotor is stabilized at the set rotation speed and stops upon stopping (decelerating) the rotation of the rotor.
In a high-speed centrifuge designed to rotate at, for example, 40,000 rpm or more, a rotor is rotated in the state where a rotation chamber is depressurized by a vacuum pump in order to prevent the overheating of the rotor due to the friction with air during a high-speed rotation. An oil rotation vacuum pump is used as the vacuum pump in many cases, and generally an oil diffusion vacuum pump is connected in serial thereto so as to serve as a vacuum pump assisting the oil rotation vacuum pump. In addition, in order to maintain the rotor at the set temperature, the rotation chamber is provided with a cooling device.
As a vacuum device manufactured by combining the oil rotation vacuum pump with the oil diffusion vacuum pump, for example, a technology is known in JP-2007-198392-A. The technology disclosed in JP-2007-198392-A is proposed as a manufacturing facility, and describes that a vacuum arrival time is reduced and energy is saved. However, in the centrifuge, since the vacuum operation is repeated in the order of “depressurization→depressurization cancellation→depressurization” whenever performing a centrifugal separation operation, an oil temperature state of oil upon activating the oil diffusion vacuum pump is different for each operation. Accordingly, since the time until arriving at a predetermined vacuum degree is different for each operation, it is not easy for the user to estimate the time until arriving at the predetermined vacuum degree.
Meanwhile, in the centrifuge available in the market, a sign indicating a middle vacuum (133 Pa) or a high vacuum (13.3 Pa) or a value of a vacuum degree is directly displayed on a display unit. However, the centrifuge having a function of estimating and displaying the time arriving at the middle vacuum (133 Pa) or the high vacuum (13.3 Pa) is not introduced into the market yet. In addition, in the description of the present specification, a low vacuum indicates the range from the atmospheric pressure to 133 Pa, and a middle vacuum indicates the range from 133 Pa to 13.3 Pa, and a high vacuum indicates a pressure of 13.3 Pa or less.
In the known vacuum device manufactured by combining the oil rotation vacuum pump with the oil diffusion vacuum pump, the oil rotation vacuum pump is used as a main pump, the oil diffusion vacuum pump is used as an auxiliary pump, and the rotor is controlled so as not to rotate at a predetermined rotation speed (for example, a rotation speed of 5,000 rpm without an influence of overheat due to air resistance) or more when the predetermined vacuum degree is not obtained. For this reason, when starting the centrifugal separation operation, the user has no idea about the time until the depressurizing (vacuum) state where the rotor is able to rotate at the set rotation speed. Particularly, in a super centrifuge having a rotation speed of 40,000 rpm or more, since the rotation energy of the rotor is large, it is important to check whether the rotor normally rotates. For this reason, generally, the user leaves from the centrifuge after checking that the rotation of the rotor arrives at the maximum rpm. However, if there is no information on how long the depressurizing operation is performed until the predetermined vacuum degree or when the rotation of the rotor starts, the user waiting before the centrifuge feels trouble.